A class of waves in a deformed viscoelastic solid

A small-amplitude plane sinusoidal wave is propagated in an isotropic nonlinear viscoelastic material Subjected to a static pure homogeneous deformation. The wave is polarized along one of the principal directions for the pure homogeneous deformation. The normals to the planes of constant phase and amplitude for the wave are perpendicular to each other and lie in the principal plane normal to the direction of polarization. It is found that the complex slowness for such a wave is independent of the orientation of the direction of propagation in the principal plane. The three complex slownesses corresponding to a particular class of waves of this type polarized along the three principal directions satisfy a relation which is independent of the detailed form of the constitutive equation.